In the prior art there is a wide range of ligatures, which are most commonly made out of metal, such as brass, but can also be made out of leather, wire mesh, rubber and plastic, among other materials. They have different fitting systems, adjustable and fixed, with different contact surfaces where the reed is supported, to highlight or overshadow some sound frequencies.
The qualities of some prior art ligatures are chosen for particular uses depending on the type of music or type of mouthpiece. Some ligatures are specific to the brand and model of the mouthpiece; they are purchased as a set (mouthpiece-ligature) and can only be used exclusively for that mouthpiece, either by the particular format or insert, or by its specific functional system.
Features Per Register:
The general features of each of the registers are due to the reed having the same dimensions both for low and high notes. Therefore, it is responsible for supporting different vibration stresses with respect to the note that is generated according to the functional length of the instrument tube and to the lip pressure required to keep it within the musical parameters.
Overall and considering the synesthesia, the best performance occurs in the middle register. The differences in volume and sound quality of the extreme registers constitute a point to solve.
Sound Tuning and Character:
Some sounds are more forced and unstable than others within the musical scale. These changes in sound behavior are a consequence of different stresses experienced by the cane, which in turn varies the tuning and the airflow.
While manufacturing the instrument, this defect is partially compensated by permanently adjusting the size of the chimneys. It should be noted that the stability of an instrument with respect to these features varies according to manufacturing quality.
Nonetheless, there are zones, and even notes in particular and in the entire register, which respond differently to the emission of constant sound and dynamic, some notes are unstable in tuning, some in volume, some in sound quality, and others vary their behavior completely in relation to different musical intervals.
The changes that are needed from the performance to compensate these inherent defects of the instrument affect the effort level of the instrumentalist, sacrificing musical expression.
The extent of the mobility margins to correct these defects to obtain more uniformity in sound and tuning in the entire register, constitute a point to solve.
Dynamics:
The ability to achieve both the minimum and maximum volume on the same note, always maintaining the sound quality and tuning in the entire register, is a goal sought by both performers and instrument manufacturers.
While this may be compensated by the skill of the performer, there have been physical approaches to enhance these skills, from creating instrument models to accessories that form the sound generator:
Aspects to Solve Regarding the Typical Defects of Prior Art Single-Reed Instruments
The mouthpiece itself is a continuation of the general tube of the instrument and is adapted so that the performer can direct air through it generating a sound which will be projected into the tube of the instrument. The latter receives the sound, amplifies it and, depending on its shape, may modify it by highlighting or overshadowing some frequencies, but its function is conditioned by the source of the sound.
The sound originates in the cane, its characteristics depend on the frequency range of the cane, and the frequencies are proportionally related to the mass volume that acts as a vibrating body, i.e. the more the reed surface vibrates in all of its dimensions, more rich in harmonics is the sound. The reed, in turn, cannot vibrate without being attached to the mouthpiece as the resulting space on the mouthpiece tip after being coupled is what allows the passage of air, which acts as energy and produces the vibration of the reed from the thinnest area.
When the reed is attached to the mouthpiece by means of the ligature, it loses vibratory properties in the pressure area where it is held.
The clamping pressure affects the general sound, and this latter can vary depending on the area of the cane affected by such pressure; as it is known, the cane contains—before a vibration—different frequencies in all its dimensions. For example, if the pressure area belonged to the low frequencies this would be perceived with a more strident general sound.
The ligature serves to clamp the reed and, for this reason, the vibratory behavior of the reed depends on it and thus the general result of the sound, which in him is projected through the mouthpiece to the general instrument tube.
Sound quality is measured by the possibilities the performer may have to control a sound in the following aspects:                Number of harmonics to compose a personal sound with respect to the choice of musical criteria (increased tonal possibility).        Wider dynamic range (volume) without loss of tonal possibilities.        Full control of tuning without sacrificing tone and dynamics.        
Another aspect to consider is the table angle relative to the clamping of the cane. Since the reed must be clamped in the area prepared to perform the fitting, it requires a wide pressure strip to prevent side movements turning around a point over the table plane. Therefore, the ligature band or the contact surface should have two or more pressure points, or may be of uniform contact over a wide area.
The more surface is longitudinally embraced, firmer and more divided is the force in crosswise direction.
Given the mouthpiece general shape, the table angle has always been a problem at the time of firmly attaching the reed without overly affecting the containment and the vibration of the same as the reed requires to be evenly and uniformly clamped over the table without affecting its structure.
The conicity of the body and the support angle generated by the table tend to destabilize the fitting pressure, and then the ligature tends to yield toward the lowest volume end.
Therefore, the more contact the ligature has over a surface in general, the better the clamping force is.
The problem that arises with prior art ligatures is that the higher the clamping force is, fewer are the possibilities of vibration of the reed, affecting the ultimate goal: “sound quality”.
Moreover, in ligatures wherein pressure is exerted on a given area of the cane in order to provide an established sound, the cane may be damaged due to pressure concentration.
Furthermore, the cane fitting control over the table angle cannot be achieved uniformly since more pressure will always be exerted toward one of the two ends of the cane.
In ligatures specifically manufactured for a mouthpiece using a mold, a way of fitting that guarantees pressure uniformity at all contact points with the cane does not exist, whether in any of the formats known as contact points with the reed.
In the case of prior art ligatures that match much better with the table angle and, consequently the pressure is uniform, it must be taken into account that table angles vary depending on the mouthpiece brand or model, which limits the ligature use, because the cane surface is never equal to another one. Furthermore, it should be noted that the performers often use various mouthpiece types, according to the need and occasion.
Ligatures manufactured with materials copying the general shape of the mouthpiece, such as the ones made of leather, rubber or textile materials, work very well regarding the reed response to a vibration, but they are limited in tonal possibilities and in dynamics, since the reed is contained by a material with elastic properties which makes the cane vibrate in a particular and very specific manner. Such prior art ligature types are used for specific sonorities.
The ligature location on different points along the table is also a tonal variation possibility, if the ligature is positioned closer to one end of the mouthpiece, as for example towards where the mouth is located, a more centered and with less volume possibility is obtained. By contrast, if the ligature is located towards the side where the mouthpiece is coupled to the instrument, the sound is broader, aggressive and has more dynamics possibilities. This is due to changes in length of the zone of the cane that is vibrating more freely, from the pressure point to the tip of the cane.
These location possibilities are generally limited for most prior art ligatures, as they work better in some points than in others, as the conicity of the mouthpiece conditions the quality of the clamping radial force. This is because the length of the utilized ligature hand varies according to the diameter of the contact area with the mouthpiece.
In summary, prior art ligatures condition the sound quality and a cane clamping element which can balance the relationship between clamping quality and the maximum sound quality has not been achieved.
In cases where the known ligatures provide a certain feature, the loss of some vibratory behavior of the reed is, on the other hand, suffered, either in volume or sound character.
To avoid pressure concentration, some ligatures comprise metal rounded plates to partially surround the cane in order to provide an even and uniformly distributed support, so as not to damage the reed (see FIG. 1c). However, it is known that a uniform distribution is detrimental to the sound quality since it limits the vibration of the reed, as it will be explained in detail later.
Ligatures which present minimum contact with the mouthpiece, known in the prior art, balance a bit more this relationship. As the ligature has fewer support points over the mouthpiece body and more over the cane, the reed vibrates more freely because it has a little more vibration mobility with respect to the table angle. In this case, the ligature body in its entirety is the one that suffers an elastic stress to allow this movement.
Some patent applications using pivoting means to improve the fitting and clamping quality are referenced below:
U.S. Pat. No. 5,623,111 discloses a ligature having a fitting system that uses a transversal screw which enables a more practical and effective general clamping exerting a more equitable pressure from the band ends over the support plate. It offers the possibility to replace different support plates that affect different cane areas giving sonority options. However, these sonority options are applied to the cane in a forced manner. The support plates are wedged on the fitting screw center which is transversely located over the bottom area forming a support with pivoting wedge. The function of this pivot system is to rotate the screw during the ligature fitting process without affecting the plate position. Once this fitting process concludes, the pivot system is annulled.
PCT Patent Application No. WO 2006/016061 A1 discloses a ligature comprising a pivoting means enabling its body to adjust to that of the mouthpiece in its upper support, thereby allowing some mobility margin for a better adaptation to the mouthpiece body together with the cane. The mobility angle is limited by the ligature hand once it makes contact by means of the fitting. Accordingly, its mobility is annulled during the operation not being capable of vibrating separately from the mouthpiece. The area making contact with the cane belongs in a fixed manner to the ligature band and responds according to the adaptation margins that allow the contact points over the mouthpiece body. Moreover, the pivoting movement is also limited because it is divided into two supports located at the band's ends, whose axes are directed in different angles. The band curvature corresponds to the mouthpiece body curvature forming a circle from the frontal perspective, and the axes direction tends to be located towards the center of the circumference. Therefore, general pivoting movement of the two supports does not correspond to the same axis. In conclusion, the operation points to the relationship between the ligature and the mouthpiece and the result in terms of improvement on the reed fitting and clamping is a consequence.
U.S. Pat. No. 8,217,248 B1 discloses a ligature which allows a better adaptation of the reed over the mouthpiece table. Its operation points to the relationship between the ligature and the cane, and it is applied to both the ligature body and the support plate, thereby composing a device that works together. The ligature body acts as an elastic means on torsion mode, applied to a minimum contact point over the mouthpiece body upper area, which allows a better adaptation of the support plate position over the cane. This elastic means on torsion mode only acts when the ligature is fitted by the general screw located at the bottom area exerting pressure on the cane. The support plate is supported at the general fitting screw tip by means of a smaller screw that allows some movement of the plate, and is only trapped by the limit which the head diameter of such screw presents. This system allows support plates replacement or adjustment. Plate mobility parameters allow the fitting screw to rotate on its axis. They also allow the plate to partially fit its support angle relative to the table angle; this mobility is limited, by the lateral torque exerted by the screw and by the limit provided by its head. The pivoting mobility is partial and is limited by the position of the ligature body, and also depends on the mouthpiece model since when the table angle of a mouthpiece model is very pronounced, the pivoting capacity is lower. As it presents a minimum support point, and none over the mouthpiece sides, it does not allow manipulation to move the mouthpiece when correcting the general instrument tuning, causing that when taking the sound generator (mouthpiece-cane-ligature) with the hand, the ligature moves sideways or slips off.
As can be observed, none of these applications have succeeded in solving all the aspects mentioned above.